Transcript for US Ebola Patients 'Improve Dramatically' From Experimental Serum

The bullet scare. And a promising news coming out of Atlanta where that doctor infected with the virus. Is doing better in fact ABC news fight out that doctor can't Britain's condition improved within. Just twenty minutes after getting an experimental. Anti serum. -- when I'm down Cutler in New York in this story to doping now doctor Bradley's wife also sent her husband is improving all of this possibly a good sign. That the other infected American who will soon be treated at that same hospital. -- and arrive -- Gonzales story reporting from Atlanta. Prepping for another were able patient doctors at Emory university hospital in Atlanta say they're ready to treat -- second American infected with the virus. Tonight Nancy white -- is expected to leave Liberia where she's battling the deadly disease just -- fighting. -- -- -- He's he's treatment. You can eat a little bit because fluid. Shall travel here on the specially equipped medical evacuation plane. The same one used to transport her colleague doctor -- Brantley to this hospital doctors say his health is improving the signs so far are very promising. We've now learned both Brantley and rival were given an experimental serum in Liberia but experts stress there is no proven cure for Ebola which is why they're coming here. Where doctors can treat their symptoms giving them a better chance at recovery than they would've had if they stayed in West Africa. The death -- spiking they -- with more than 800 reported deaths in this outbreak including a second confirmed Ebola death in Nigeria. A Doctor Who treated this liberian American -- a patient there before he died now also succumbing to the virus. Experts saying everything possible is being done to keep the disease from spreading -- year. That's understandable that with a deadly disease. How people are concerned but the plain truth is that we. And rifle is brought here everyone who comes in contact with her will be in full -- -- -- and like Brantley shall be kept in -- -- isolated room here away from other patients. -- Gonzalez ABC news Atlanta. By Marcy thank you vessel for the latest now on those patients or whatever and ABC's Eric trustees also -- the story developing at this hour in Atlanta so. -- what is this mysterious anti Sarah. Well it's just that it's an experimental serum -- Produced by a company in San Diego and it found its way accident special Christian missionary hospital in Liberia where doctor Brantley and Nancy right ball had been volunteering. Through an intermediary with the National Institutes of Health that was not given as part of an official channels but. The missionary it was turned on to this experimental serum. -- and it seemed who have worked almost instantly on doctor Brantley. Initially there was some concern there wasn't enough of the experimental drug to give both patients to dose. Finally they decided to treat doctor -- first when he took it we're told he started dramatically improving within about twenty minutes. And now what is the Richmond and going forward for that second American effectively. She makes her -- Nancy rifle was also given a dose of this experimental serum and her condition has improved. She's now -- we're told she's hungry she asked for liberian potato soup. And it may sound innocuous but that's actually really important public health experts tell us that. Usually Ebola patients don't -- whether because of -- vomiting condition -- the state of their deteriorating health. To see her have an appetite is really encouraging. And the missionary group that she -- -- says she is fit to travel -- come here to Emory university hospital sometime on Tuesday for supportive care. They can't really give her any more drugs there isn't -- known cure. But they can make sure that her vital signs are are healthier blood pressure her breathing. So her body can fight the infection on its own -- let me ask you this because there was some confusion as far as who exactly receive that kind of treatment -- was thought initially. That Nancy was the only recipient. If there was some initial confusion and apparently -- there was some concern that there wasn't enough of this experimental serum. For both of the American patients they finally decided to treat doctor Brantley -- -- first. He showed that dramatic improvement. Within twenty minutes maybe into an hour and finally those dramatic images here over the weekend when he was able to walk on his own in a protective suits. Into the hospital it's done -- even his family and friends who had been told to brace for the worst. I think -- stunned even his doctors who were expecting him to appear here in far worse shape than he did. When Nancy rifle was given the second. Dose of this experimental serum she -- seems to have stabilized got her appetite back and social beyond that same air ambulance on her way to Atlanta. Sometime we believe tonight. American time. Before she's taken here to Atlanta firm -- continue treatment. Have we learned anymore about how exactly these two Americans contracted the virus. The Centers for Disease Control is still trying to figure out how these two Americans contracted Ebola. But strong suspicion is now. Falling on a liberian national who happen to work at the missionary hospital in Liberia where these two Americans were volunteering. This was not a trained health care professional this was someone hosing down the rooms. Just doing cleanup work. And that's actually encouraging. Some who would come into contact with these doctors because they say exposure to this liberian national would have been limited. What about those now at every hospital that will be treating both of these patients what -- we heard about concern or worry. -- their own safety for the hospital staff the doctors that'll be working in close contact. There's a team of about six. Mean people that that work on the east two patients or -- now working on doctor Brantley and will work on Nancy -- The specialized nurses one of whom we're told gave up a vacation in Cancun just to be part of this team and an infectious disease specialist. From the Centers for Disease Control from here at Emory University. All of them want we're told to be on this team they -- want to be able to provide the care that they believe only Emory university hospital. Can provide and so there's no concern among the team. Outside in the community we've heard especially on social media there is some wider concern about the decision. To bring in a bullet patient here to the United States for the first time. And some criticism about whether that puts the public at risk because we've heard there's low risk but that doesn't mean no risk. The Centers for Disease Control takes that as a moment of education they say transmitting people it is really hard no casual contact it's not airborne. It has to be transmitted through bodily fluids. And so the CDC says. These patients can can be isolated and therefore if -- can be contained. So plain that forward -- -- as far as the overall public safety the virus has killed 800. 87 people that we know up. It is still spreading in West Africa what are the chances of the US might actually ban travel altogether. From some of those affected countries. -- of the Centers for Disease Control has already put in its most stringent level three travel warning. And that makes -- bola and in the CDC's mind as serious as it's ours -- the earthquake in Haiti in terms of no go for travel. And we're not sure whether there would be any additional restrictions. But the Centers for Disease Control the same time is sending people public health experts into West Africa the CDC says the best way to keep Americans safe. Is to get -- Bullock at its source in the affected countries especially Liberia Sierra Leone Guinea now Nigeria where as you say. The virus has killed almost 900 people. The CDC believes it can be contained it may take three to six months to do it but they're really going to try so it doesn't spread beyond the countries where it is now. And of course -- focus right now on those two Americans one being treated right now in Atlanta. The other and -- ABC's Eric -- in Atlanta following the very latest on this story -- thank you for that. And of course you can keep up with the story in real time by downloading ABC news happened started -- sort -- with updates on the go. For now I'm Dan --

This transcript has been automatically generated and may not be 100% accurate.